1. Field of the Invention
This invention relates to a zoom optical system whose optical axis is bent, and in particular, to an optical path bending zoom optical system in which an optical path bending element is used in order to achieve a slim design with respect to the depth direction of a digital camera, a personal digital assistant, or a mobile phone, mounting a zoom optical system.
2. Description of Related Art
In imaging optical systems incorporated in compact cameras, personal digital assistants, and mobile phones which use electronic image sensors such as CCDs, the need for compact design, notably slim design, is emphasized.
As the prior art of the optical system of this type, for example, there is a four-lens-unit zoom optical system whose optical path is bent. This optical system has an optical member including a plano-convex lens and a rectangular prism which are cemented to each other in a third lens unit.
Further, for example, there is an optical system designed to impart optical power to an optical path bending prism.